(173d) Research on Dry-Processing Technology for Reconverted Resources Fluorine from Waste Chlorofluorocarbons

The new dry type process technology of recovering fluorine from the waste chlorofluorocarbon which is global warming gases as resources is developed. The feature of this technology is carrying out the dry reaction of the exhaust gas which decomposed chlorofluorocarbon to calcium carbonate at low temperature, and is making it convert into the fluorite of high purity. The gas-solid reaction characteristics of steam decomposition gases of chlorofluorocarbon with air and calcium carbonate were investigated. The gas-solid reaction of the chlorofluorocarbon decomposition gases, in which the concentration of HF is about 30 % and of HCl is about 15 %, and calcium carbonate, of which grain size is 1-2 mm, was conducted at the temperature of 200 degrees C and SV of 1860 h^-1. It was found that HF concentration contained in off-gas from fixed-bed reaction furnace before HF break-through time was very as low as less than 1000 ppm, on the other hand HCl concentration becomes high with the range of 10-15 %. This result shows that fluorine is alternatively absorbed by calcium carbonate in a fixed-bed reaction furnace. Moreover, the fluorite purity of the sample by which the reaction progressed comparatively into the fixed-bed reaction furnace became about 94 %. Also, we demonstrated that the calcium chloride generated at chlorine and calcium carbonate reacting replaces calcium fluoride gradually with advance of a reaction. From these results, the implement ability of the dry-type reconverted resources technology of waste chlorofluorocarbon can be verified.